EHF secure communication device

ABSTRACT

A communication device employs a contactless secure communication interface to transmit and receive data with a computing device using close proximity extremely high frequency (EHF) communication. The communication device and the computing device periodically initiate a discovery operation mode, whereby the devices periodically transmit identifying information about the respective devices and listen for identifying information from the other device. Upon completion of the discovery mode operation, the devices enter a link-training operation mode and exchange capability information about the respective devices. During transport mode operation the communication device employs methods to manage access to data stored on the communication device by encrypting the data using one or a combination of training information or capability information as a basis for generating an encryption key.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 14/135,458, filed Dec. 19, 2013, and entitled “EHF SecureCommunication Device,” which claims the benefit of U.S. ProvisionalPatent Application No. 61/779,579, filed on Mar. 15, 2013, and U.S.Provisional Patent Application No. 61/799,510, filed on Mar. 15, 2013,each of which is incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

This disclosure relates an electronic communication device with a securecontactless communication interface.

2. Description of the Related Arts

Advances in electronic communication device technology have producedsmaller devices with increased storage capacity, and faster transferrates. Similar gains, however, have not been realized in theconnectivity technology to transfer data to and from these devices. Forexample, a portable data card, such as a Secure Digital (SD) card, isnow equipped with communication functionality and utilizes mechanicalconnectors to deliver a transfer rate of around 20 MB/s.

Transfer rate for portable data cards or storage devices like SD cardsis often limited by the connection interface and the power required totransfer data. Transfer rate also provides a practical limitation on thestorage capacity because at some point it becomes impractical to waitfor a large amount of data to be transferred over a low data rateinterface. Existing contact-based connectors may limit the form factor,transfer rates, ESD capabilities, and device ruggedness. Otherconnection interface technologies utilize wireless broadcasting methodsto improve data transfer rate. Broadcasting techniques, however, maycompromise the security of the data transfer.

SUMMARY

Embodiments include a device and an approach for managing access toinformation stored on a communication device over a contactless securecommunication interface by using a communication interface configured totransmit and receive data using close proximity extremely high frequency(EHF) communication. The communication device periodically initiates adiscovery operation mode, whereby the communication device periodicallymonitors to detect identifying information from an EHF transmissionreceived from a computing device or another communication device. Thecommunication device also periodically initiates a discovery mode,whereby the computing device periodically transmits indentifyinginformation to the computing device. In one embodiment, the identifyinginformation includes a beacon transmission (e.g., a series of unencodedor encoded pulses). When the communication device detects theidentifying information from the computing device, the communicationdevice transmits identifying information about the communication deviceto the computing device. The computing device, in turn, when detectingthe identifying information received from the communication device,transitions from the discovery mode to a link-training mode.Subsequently, the communication device also enters the link-trainingmode.

During the link-training mode, the communication device and thecomputing device monitor whether a link-training pattern is receivedfrom the computing device and the communication device, respectively. Inone implementation, the transmitting device sends a specified datapattern to enable the receiving device to optimize receiver settings(e.g., signal levels, amplification, or other signal conditioningtechniques). The receiving device, in turn, enters a learning mode andsends an acknowledgement to the transmitting device when the receivingdevice completes training. In one embodiment, the receiving device exitsthe learning mode when a threshold number of training cycles have beenreceived by the receiving device. When the receiving device has notreceived a threshold number of training cycles within a specified timeperiod (e.g., 100 ms), the receiving device sends a message to thetransmitting device indicating that link-training has not beencompleted.

The link-training pattern is a data pattern that is suitable to enablethe communication device and the computing device to determine settingssufficient to receive and detect information provided by thetransmitting device (i.e., the computing device or the communicationdevice). In one example, the data pattern is 1 μs of alternating “1” and“0” levels followed by an idle level, changing every third period of areference clock coupled to the transmitter circuit 305 and the receivercircuit 310. In another example, the link-training pattern may usemultiple EHF levels or codings in addition to idle levels to determinethe settings. The reference clock may be of any suitable clock frequency(e.g., 266 MHz) sufficient to exchange information between thecommunication device 100 and the computing device 300. In oneembodiment, the receiving device operating in link-training modeevaluates attributes of the received training pattern to determinewhether the communication link between the transmitting and thereceiving device is suitable to exchange information between the twodevices. For example, in one embodiment, the receiving device operatingin link-training mode qualifies the strength of the received trainingpattern to determine whether proximity between the devices satisfies athreshold distance.

In one embodiment, upon completion of the link-training period, thecommunication device and the computing device will exchange capabilityinformation about the respective devices, including, for example, devicetype, transport mode, vendor information, protocol information, andauthentication information (e.g., encryption information). Whenreceived, the receiving device validates the capability informationagainst its own capability information (e.g., transport modecapabilities), and transitions to a transport mode to exchangeinformation between the two devices. In one embodiment, during transportmode the communication device employs methods to manage access to datastored on the communication device. In one example, the communicationdevice employs an authentication protocol using a portion of thecapability, information or attributes of one or a combination ofreceived or transmitted EHF information.

The features and advantages described in the specification are not allinclusive and, in particular, many additional features and advantageswill be apparent to one of ordinary skill in the art in view of thedrawings and specification. Moreover, it should be noted that thelanguage used in the specification has been principally selected forreadability and instructional purposes, and may not have been selectedto delineate or circumscribe the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the embodiments of the present disclosure can bereadily understood by considering the following detailed description inconjunction with the accompanying drawings.

FIG. 1 illustrates a plan view of a communication device, according toone embodiment.

FIG. 2 illustrates an arrangement of a communication device, accordingto one embodiment.

FIG. 3A illustrates a block diagram of a close proximity extremely highfrequency (EHF) communication interface included in a communicationdevice of FIG. 1 and a computing device, according to one embodiment.

FIG. 3B illustrates a block diagram of another close proximity extremelyhigh frequency (EHF) communication interface included in a communicationdevice of FIG. 1 and a computing device, according to one embodiment.

FIG. 4 illustrates a graph that shows the timing of multiple timercycles for transmitter and receiver timers included in a pair ofcommunication interface units of FIG. 3B, according to one embodiment.

FIG. 5 shows a block diagram illustrating a time of flight calculationof information exchanged between communication interface units of FIG.3B, according to one embodiment.

FIG. 6 illustrates a block diagram of a communication interface unitthat includes an encryption module, according to one embodiment.

FIG. 7 illustrates a flowchart of a method for controlling access to acommunication device, according to one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

The Figures (FIG.) and the following description relate to preferredembodiments of the present disclosure by way of illustration only. Itshould be noted that from the following discussion, alternativeembodiments of the structures and methods disclosed herein will bereadily recognized as viable alternatives that may be employed withoutdeparting from the principles of the present disclosure.

Reference will now be made in detail to several embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying figures. It is noted that wherever practicable similar orlike reference numbers may be used in the figures and may indicatesimilar or like functionality. The figures depict embodiments of thepresent disclosure for purposes of illustration only. One skilled in theart will readily recognize from the following description thatalternative embodiments of the structures and methods illustrated hereinmay be employed without departing from the principles of the embodimentsdescribed herein.

Example Communication Device

FIG. 1 is a plan view illustrating a communication device 100, accordingto one embodiment. As shown in FIG. 1, the communication device 100 is aportable device with a form factor similar to a credit card, securityfob, smart card, or other portable storage device. The communicationdevice 100 includes a data storage medium, which may include one or morememory devices 110, communication interface units 105, controllers 115,power management unit 120, an inductive coil 130, and a power interfacecircuit 135 all arranged and disposed on substrate 125 within thecommunication device. The memory device 110 may be volatile memory, suchas random access memory (RAM), or non-volatile memory, such as flashmemory, or another device that employs other suitable data storagetechnology, and data may be written to and read by the controller 115.The controller 115 manages the flow of data between a communicationinterface unit 105 and one or more memory devices 110. The controller115 may be a separate integrated circuit, integrated into a memorydevice 110, or may be included in a processor (not shown) included inthe communication device 100.

The communication interface unit 105 includes circuitry configured totransmit and receive close proximity extremely high frequencyelectromagnetic energy (i.e., transmissions) as further discussed withreference to FIG. 3. Examples of a communication interface unit 105 aredescribed in U.S. patent application Ser. No. 13/471,052, which isincorporated by reference in its entirety. The power management unit 120is a contactless power system, such as an inductive power system. Forexample, as shown in FIG. 1, the power management unit 120 includes aninductive coil 130 configured to receive electromagnetic energy andconvert the received electromagnetic energy to electrical energy, and apower interface circuit 135 configured to distribute electrical power tothe devices on the communication device 100. The power interface circuit135 may also store part of the generated electrical energy in an energystorage unit, for example, a battery (not shown).

The substrate 125 may be a printed circuit board (PCB) or otherdielectric material that includes an upper and a lower planar surfaceand multiple edges for a perimeter. In one example, one or morecommunication interface units 105 are positioned on the substrate 125 toprovide communication between components coupled to the respectivecommunication interface units 105 co-located on a planar surface of thesubstrate 125. In another example, one or more communication interfaceunits 105 are placed on an upper and lower planar surface of thesubstrate to provide communication between components included on asubstrate that includes corresponding communication interface units andarranged above or below the substrate 125, as further described withreference to FIG. 2. In a further example, one or more communicationinterface units 105 are arranged on the perimeter of the substrate 125to provide communication between the communication device 100 and acomputing device 300 that includes a corresponding communicationinterface unit, as further described with reference to FIG. 3.

As described herein, the communication device 100 may also be referredto as a client device, and in particular when the communication device100 communicates with a host computing device. In some embodiments, ahost and a client device are positioned at distance and alignmentrelative to each other sufficient to permit the correspondingcommunication interface units 105 on the client and host devices toexchange information.

The communication device 100 also includes a covering 140 or sealinglayer disposed on the components arranged on the substrate, such thatthe covering 140 forms a hermetically sealed communication device 100.In one embodiment, the covering 140 is composed of a dielectric materialor other non-electrically conductive material suitably transparent toelectromagnetic energy in the EHF range (typically, 30-300 GHz). Inanother embodiment, the covering 140 is composed of a metallic orelectrically conductive material suitable to direct, shield, orotherwise manipulate the propagation of EHF energy.

The communication device 100 may be backward compatible with SD, MultiMedia Card (MMC), or other standards and include one or a combination ofan EHF transmitter and EHF receiver. In one embodiment, thecommunication device 100 is water-proof and immune to electrostaticdischarge (ESD) events. In one embodiment, the communication device isactivated (i.e., switched into a power-on operation mode) responsive toreceiving an EHF transmission or transferring information to anotherdevice. In one embodiment, the communication device 100 is self-powered.In another embodiment, the communication device 100 is powered through awireless transmission means.

FIG. 2 illustrates an arrangement of a communication device 100,according to one embodiment. The communication interface units 105 maybe configured to transmit or receive an EHF transmission directionallyor hemispherically. For example, the pair of communication interfaceunits 105A and 105C is disposed facing each other on separate substrateswithin a communication device 100. As shown in FIG. 2, the pair ofcommunication interface units 105A and 105C are is disposed and alignedon a lower surface of substrate 125A and on an upper surface ofsubstrate 125B, respectively, and configured to transmit or receive EHFtransmissions in a direction facing each other. The pair ofcommunication interface units 105B and 105D is arranged and configuredin a manner similar that described for the pair of communicationinterface units 105A and 105C to form a vertical contactless (i.e.,non-physical connection between transmit and receive devices)communication path between communication interface units 105A and 105C.The configurable directionality of an EHF communication transmitted orreceived by a communication interface unit 105 enables inter-layercommunication paths to be created to allow information to be exchangedbetween components disposed on substrate 125A and components disposed onsubstrate 125B. For portable communication devices, using astacked-substrate configuration with communication interface units 105creating contactless inter-layer communication paths allows storagecapacity to scale while maintaining the footprint of the communicationdevice.

In one embodiment, the spatial energy distribution of the EHFcommunication signal transmitted and received by a communicationinterface unit 105 may be relatively wide compared to the form factor ofthe communication interface unit 105. In turn, the substrates 125A and125B may be substantially physically aligned in one axis with a physicalseparation in the other axis. For example, as shown in FIG. 2, thesubstrates 125A and 125B are aligned along the x-axis such that one orboth of the communication interface unit pairs 105A and 105B and 105Cand 105D can exchange information. Also, as shown in FIG. 2 thesubstrates 125A and 125B are separated by a distance d along the y-axis.In one implementation, the distance d is specified within a toleranceranging from approximately 1 mm to approximately 5 cm withoutsubstantially affecting the communication channel between thecommunication interface unit pair 105A and 105C and the pair 105B and105D. In other implementations, the substrates 125A and 125B arearranged in other alignments suitable to allow the communicationinterface unit pairs 105A and 105C and 105B and 105D to exchangeinformation. Other alignment configurations employ one or a combinationof discrete angles, waveguides, or other transmission medium to directan EHF transmission along a specified path between paired communicationunits 105.

As shown in FIG. 2, the communication channel between pairedcommunication interface units 105 is contactless. Intervening structureswithin the communication path between facing communication interfaceunits 105 can be designed in order to not disrupt the exchange ofinformation between the paired communication interface units 105. Forexample, in one embodiment, in a stacked configuration pairedcommunication interface units 105 are disposed on nonadjacent layers andform a transmission path, such as a contactless conduction path, thattraverses one or more intervening layers. In some cases, the interveninglayers are composed of dielectric materials or other materialstransparent to EHF emission. In one embodiment, regions of anintervening layer in the transmission path of paired communicationinterface units 105 are configured to be free from materials, such asmetal components, that would impair communication between transmittingand receiving EHF devices across the transmission path. In oneembodiment, regions of an intervening layer comprise electricallyconductive materials configured to operate as an antenna (e.g., a slotantenna) to direct an EHF communication along a particular transmissionpath. In another embodiment, one or more intervening layers may includean opening or aperture on multiple intervening layers in the conductionpath between paired communication interface units 105. The aperture isconfigured to have a size sufficient to pass an EHF transmissionundisturbed such that communication between paired communicationinterface units 105 can be maintained. One or a combination ofadditional and alternative arrangements of substrates 125 andcorresponding paired communication interface units 105 may be arrangedas a communication device 100 assembly, as described in U.S. patentapplication Ser. No. 13/471,052, which is incorporated by reference inits entirety.

FIG. 3A illustrates a block diagram of a portable information storagesystem using a close proximity extremely high frequency (EHF)communication interface included in a communication device 100 and acomputing device 300, according to one embodiment. In one embodiment,the portable information storage system includes a communication device100 and storage device reader 300. The communication device 100 may beany suitable storage system capable of reading and writing electronicinformation, as previously described in reference to FIG. 1. Moregenerally, the communication device 100 may also be a component orstorage subsystem that is integrated into another device or systemhaving a form factor larger than a mobile computing device or a portablestorage device. The computing device 300 includes any suitable devicehaving information processing functionality and one or more interfacesconfigured to receive information electrically, optically,electromagnetically, or other transmission format suitable tocommunicate with the communication device 100. The communication device100 includes one or more communication interface units 105 forexchanging information with another communication interface unit 105over a transmission path. The communication interface unit 105 isconfigured to transmit and receive an EHF transmission to anothercommunication interface unit 105 over a conduction path. In particular,the communication interface unit 105 uses EHF close proximity couplingto exchange information at high data rates (e.g., 8 Gb/s) over aconduction path link ranging from approximately 1 mm to approximately 5cm using EHF frequencies (typically, 30-300 GHz). The conduction pathmay include air or a dielectric material suitable to transmitelectromagnetic energy in the EHF frequency range.

In one embodiment, the communication interface unit 105 includes atransmitter circuit 305 and a receiver circuit 310 coupled to aninterface controller 320. The communication interface unit 105 alsoincludes a transducer 315 coupled to the output of the transmittercircuit 305 and the input of the receiver circuit 310. The transmittercircuit 305A is configured to receive electrical information,representing information stored on the memory device 110, via theinterface controller 320A and send the received electrical informationto the transducer 315A for conversion to an EHF signal for transmission.In one embodiment, the transmitter circuit 305 operates in conjunctionwith interface controller 320 and transducer 315 to convert electricalinformation into an EHF transmission and to transmit a modulated EHFtransmission. The receiver circuit 310 is a circuit configured toreceive the EHF transmission from a transmitter circuit 305 usingtransducer 315, convert the received EHF transmission to electricalinformation, and provide the converted electrical information tointerface controller 320 for further processing. Further details of thedescription of the transmitter circuit 305 and receiver circuit 310 aredescribed in U.S. patent application Ser. No. 13/760,089, which isincorporated by reference in its entirety.

In one embodiment the transducer 315 is a folded dipole or loop antennaand configured to operate at radio frequencies in the EHF spectrum. Thedimensions of the transducer 315 are suitable for operation in the EHFband of the electromagnetic frequency spectrum. In one embodiment, thetransmitter circuit 305 and the receiver circuit 310 are coupled to asingle transducer 315. In other embodiments, the transmitter circuit 305and the receiver circuit 310 are coupled to separate transducers 315.

For example, as shown in FIG. 3B, a communication interface unit 105includes multiple transducers 315A1 and 315A2 and multiple interfacecontrollers 320A1 and 320A2. As shown in FIG. 3B, in the transmitterpath, interface controller 320A1 is coupled to the input of transmittercircuit 305A. The output of the transmitter 305A is coupled to the inputof transducer 315A1. Similarly, in the receiver path of thecommunication interface unit 105, interface controller 320A2 is coupledto the output of the receiver 310A. The output of the transducer 315A2is coupled to the input of the receiver circuit 310A. The interfacecontrollers 320A1 and 320A1 are coupled together to exchangeinformation, such as timer information as will be later described withrespect to the link-training mode operation. The computing device 300may be configured in a similar manner as described with respect to thestorage device 100 in FIG. 3B.

Returning to FIG. 3A, the interface controller 320 conditionsinformation accessible by the communication device 100 or the computingdevice 300 for transmission by the transmitter circuit 305 and receptionby the receiver circuit 310. Information conditioning applied to theinterface controller 320 includes modulating transmitted EHFinformation, encoding electrical information accessible by thecommunication device 100 or the computing device 300, and generating anidentifying message (e.g., a beacon transmission) for exchangingidentifying information about the respective devices between thedevices. Modulation schemes applied by the interface controller 320, forexample, include amplitude-shift keying modulation, or other suitablemodulation technique capable of being demodulated by a receiver circuit310 of a corresponding receiving device.

During discovery mode operation, the interface controller 320 generatesidentifying information from a sending device and detects identifyinginformation from a receiving device over a transmission path. Aspreviously described, during the discovery operation mode thecommunication device 100 and one or more computing devices 300transition from a low power state to transmit or receive identifyinginformation from another device to determine whether the other device isavailable to exchange information. The minimum latency from a low poweror powered down state to a discovery operation mode is approximately 1microsecond. In one example, during the discovery operation mode, thecommunication device 100 powers up periodically and monitors a receivechannel for identifying information from an EHF transmission generatedby a computing device 300 or another storage device. To manage power,the interface controller 320 maintains the communication device 100 inpowered down state or low power state during a substantial portion ofthe discovery operation mode relative to the portion of the discoveryoperation mode when the communication device 100 is monitoring a receivechannel. For example, the interface controller 320 may enable thereceiver circuit 310 to monitor for received EHF transmissions for 100ns and disable the receiver circuit 310 for 999,900 ns in a given cycle.In this example, the power draw of the communication device 100 isapproximately 50 mA when the receiver circuit is enabled and 5 μA whenthe receiver is disabled. Generally the on/off ratios (i.e., the ratioof when the receiver circuit 310 is enabled compared to when thereceiver circuit 310 is disabled during the discovery operation mode) isapproximately 1000:1.

The transmitter circuit 305B in the computing device 300 powers upperiodically to transmit identifying information, such as a beacon, inthe form of an EHF transmission. To manage power, the interfacecontroller 320B maintains the ON/OFF ratios (i.e., the ratio of when thetransmitter circuit 305B is enabled compared to when the transmittercircuit 305B is disabled during the discovery operation mode) to beapproximately 1:500 (e.g., 2 ms on, 998 ms off). The minimum latencyfrom a low power or powered down state to a discovery operation mode isapproximately 1,000 ms. In this example, the current draw of thecomputing device 300 is approximately 40 mA when the transmitter circuit305B is enabled and approximately 80 μA when the transmitter circuit isdisabled. In one example, to enhance data transmission security thecommunication device 100 is configured to not respond or otherwiseacknowledge receipt of a beacon transmitted by the computing device 300.

During the discover mode operation, the interface controller 320 alsoregulates the turn-on time and ON-time duration of the transmittercircuit 305 and receiver circuit 310 to ensure synchronization betweenthe beacon transmission and beacon detection operations. In oneembodiment, interface controller 320 enables the receiver circuit 310 tomonitor for received beacon for a duration sufficient to coincide orotherwise overlap with a portion of the period of the beacontransmission generated by a computing device 300. In one example, theON/OFF ratio for the receiver circuit 310A and the transmitter circuit305B are set by the respective interface controllers 320A and 320B toenable the beacon transmission generated by the computing device 300 tocoincide with multiple monitoring periods (i.e., ON periods where thereceiver circuit 310A is enabled). For example, the interface controller320A causes the transmitter circuit 305A to turn ON periodically every50 μs, and causes the receiver circuit 310A to turn ON periodically foran ON-time duration of 100 μs. This ensures overlap between transmit andreceive circuits. The ON/OFF ratio of the transmit circuit may be 1:500,while the ON/OFF ratio of the receive circuit may be 1:1000. Thelimitations of the ON/OFF ratio of the transmit circuit are limited bythe minimum beacon pulse and minimum receive circuit ON period. Forexample, if the minimum beacon pulse is 100 ns and the receive circuitON period is 100 us, the ON/OFF ratio of the transmit circuit may be setto 1:500. This ensures that if a beacon is present, the receive circuitwill be able to detect it under all circumstances. The limitations ofthe ON/OFF ratio of the transmit circuit are limited by the receivecircuit ON period and required wake-up time. For example, if the receivecircuit ON period is 100 us and the required wake-up time is 100 ms, theON/OFF ration of the receive circuit may be set to 1:1000. In anotherexample, controller 320 enables the receiver circuit 310 to monitor forreceived beacon with an ON/OFF sequence that occurs at a lower rate orfrequency (e.g., one hundredth) than the ON/OFF sequence of the beacontransmitted by transmitted circuit 305. In this example, by having amuch different rate of enabling the receiver circuit 310 versus thetransmitter circuit 305, a sufficient duration (i.e. at least one pulseof the ON/OFF sequence) can be set to coincide between the beacon sentby the transmitter circuit 305 and detected by a receiver circuit 310.In another example, the interface controller 320B of the computingdevice 300 causes the transmitter circuit 305B to chop (i.e.,periodically switch the beacon transmission ON and OFF during a beacontransmission period). In this example, the interface controller 320Bmaintains a beacon transmission with an ON/OFF ratio of 1:5 during abeacon transmission period, while maintaining an ON/OFF ratio of 1:100when the transmitter circuit 305B is enabled to transmit a beacon. Thisgives an overall ON/OFF ratio of 1:500. In another example, theinterface controller 320A of the communication device 100 maintains themonitoring period, while the interface controller 320B varies the beaconperiod. The variation may range from 10 nanoseconds to 1 second, orlonger.

In another example, the respective interface controllers use one or morereference clocks to synchronize the beacon transmission period with themonitoring period. Using a reference clock in such a manner enablesnarrower beacon transmission periods and lower beacon rates, which inturn, reduce the overall power draw for both the communication device100 and the computing device 300. In another example, the data sequenceused during the beacon period and the monitoring (i.e., listening)period are encoded, such that the transmitter circuit 305 transmits aparticular bit sequence during the beacon period and the receivercircuit 310 of the receiving device looks for the particular bitsequence in the beacon EHF transmission during monitoring mode. Thediscovery operation mode is complete when each interface monitoring unit320 in at least a pair of communicating devices determines thattransmitted and received bit sequences match during the respectivemonitoring and beaconing transmission periods.

In one embodiment, the interface controller 320 of a transmitting deviceincludes proximity-sensing circuitry configured to detect signals from acorresponding receiving device and determine based at least in part onthe detected signal whether the pair of devices are physically arrangedrelative to each other in a manner to exchange information reliably. Theproximity sensing circuitry of the interface controller 320 includescircuitry to detect an EHF transmission received from the receivercircuit, analyze attributes of the detected transmission, and decodeinformation included in the detected EHF transmission, as furtherdescribed in U.S. patent application Ser. No. 13/524,963, which isincorporated by reference in its entirety. The detected EHF transmissionmay be generated by the computing device 300 attempting access toinformation stored on communication device 100 or the detected EHFtransmission may be derived (e.g., a reflected signal) from an EHFtransmission generated by a communication interface unit 105.

In one example, the interface controller 320A is configured to detect anEHF transmission received from computing device 300 and determine therelative or actual distance between a surface of the communicationinterface unit 105A to a surface of a nearby object by detecting achange in a transmission property (e.g., an attribute of the impedance,return loss, etc.) of the transmitter side of transducer 315A caused bythe nearby object. In this sense, the nearby object may be considered atransducer field-modifying device. A change in a transmission propertyof the transmitter side of the transducer 315A produces a signal thatwhen compared with a reference signal indicates whether a nearby objectis within a threshold distance D 330 from the communication device 100,as further described in U.S. patent application Ser. No. 13/524,963,which is incorporated by reference in its entirety. The value of thethreshold distance D 330 is stored in memory accessible by the interfacecontroller 320 and is used by the interface controller 320 for furtherprocessing.

In another example, the interface controller 320A includes circuitry tocalculate a delay in the propagation time of an EHF transmission betweenthe communication interface unit 105A and the communication interfaceunit 105C. The signal propagation time represents a measure of theround-trip time or portion thereof (e.g., time of flight from thetransmitter of a first device to a receiver of a second device and viceversa) that it takes for an EHF transmission generated by thecommunication device 100 and received by the computing device 300 to bereturned to the communication device 100. The interface controller 320Aincludes circuitry to determine the propagation time between transmittercircuit 305A and the receiver circuit 310B; the receiver circuit 310Band the transmitter circuit 305B; and the transmitter circuit 305B andthe receiver circuit 310A based on attributes of the detected EHFtransmission, and generate an indication of proximity between thecommunication device 100 and the computing device 300 based on theindication.

For example, in the example shown in FIG. 3A, during the link-trainingmode, the interface controller 320A of communication device 100initiates one or more timers that count the number of clock cyclesbeginning from when training information is transmitted by a transmitteror receiver and ending when the transmitted information is received bythe same transmitter or receiver circuit as further described inconjunction with FIG. 4. In one implementation, the training informationis represented as a sequence of specified bits generated by theinterface controller 320A. In another implementation, the traininginformation is provided to the interface controller 320A from the memorydevice 110 or a source external to the communication device 100.

The interface controllers 320 operate in conjunction with thetransmitter and receiver circuits of the respective communicationinterface units 105 to start and stop multiple timers in a cyclicmanner. In one embodiment, during each timer cycle, each transmittercircuit 305 and each receiver circuit 310, in each communicationinterface unit 105 start a timer when the training information is sentby the circuit, and stop the timer when the training informationcompletes a round-trip path returning to the circuit from which thelink-training information originated. In one example, the round-trippath from the transmitter circuit 305A begins at the transmitter circuit305A, and includes the transducer 315A1, the transmission path betweenthe communication interface units 105A/B, transducer 315B1, the receivercircuit 310B, the interface controllers 320 B1 and 320 B2, thetransmitter circuit 305B, the transducer 315B2, the transducer 315A2,the receiver circuit 310A, and the interface controllers 320A1 and320A2.

In operation, the interface controller 320A starts a transmitter timerwhen the link-training information is transmitted by the transmittercircuit 305A and stops the timer when the link-training informationtransmitted by the transmitter circuit 305A is received by thetransmitter circuit 305A or interface controller 320A1 from the receiver310A via the interface controller 320A (or 320A1). This process iscontinued by the interface controller 320B (or 320B2), which starts areceiver timer when the link-training information from the transmittercircuit 305A is sent from the receiver circuit 310B to the transmittercircuit 305B via the interface controller 320B (or 320B2), and stops thereceiver timer when the link-training information transmitted by thereceiver circuit 310B is received by the receiver circuit 310B fromcommunication interface unit 105A. The interface controllers 320B (or320B1) also starts a transmitter timer when the link information fromthe receiver circuit 310 is transmitted by the transmitter circuit 305Band ending when the link-training information transmitted by thetransmitter circuit 305B is received by the transmitter circuit 305Bfrom the receiver 310B. To complete one iteration of the round-trippropagation calculation, the interface controller 320A (or 320A2) startsa receiver timer when the link-training information from thecommunication interface unit 105B is received by the receiver circuit310A, and stops the receiver timer when the link-training informationtransmitted by the receiver circuit 310A is received by the receivercircuit 310A from communication interface unit 105B.

The communication interface unit 105 sends the link-training informationat a specified time period or interval, including during periods whenother information or data is not being exchanged between thecommunication interface units 105A and 105B. The communication interfaceunit 105 uses one or more techniques to exchange link-traininginformation, including using a subcarrier, or using a coding scheme tosend the link-training information along with other information. Forexample, a novel 8B/10B coding scheme may be used to exchangeinformation between communication interface units 105A and 105B, wheretwo bits are used to carry link-training information.

FIG. 4 illustrates a graph that shows the timing of multiple timercycles for the transmitter and receiver timers included in the pair ofcommunication interface units 105A and 105B of FIG. 3B. As shown in FIG.4, the transmitter circuit 305A starts a transmitter timer at time t0,followed by the receiver circuit 310B, which starts a receiver timer attime t1 when the receiver circuit 310B receives the training informationfrom the transmitter circuit 310A. In turn, the transmitter circuit 305Bstarts another transmitter timer at time t2 when it transmits thetraining information received by the receiver circuit 310B. At time t3,the receiver circuit 310A starts another receiver timer when it receivesthe training information from the transmitter circuit 305B. To completethe first timer cycle, the respective timers stop counting in the sameorder that the timers started their respective timers. For example, attime t4, the transmitter circuit 305A stops the transmitter timer,followed by the receiver circuit 310B stopping a receiver timer at timet5, the transmitter circuit 305B stopping a transmitter timer at timet6, and the receiver circuit 310A stopping a receiver timer at time t7to complete the first cycle. In another implementation, at times t4-t11,a time stamp of the timer value of the respective timers is recordedwhile the timers continue running. In a further implementation, at timest4-t11, the respective timers stop and are restarted when the node sendsthe link training information to the next node in the communicationpath.

As previously described, in some implementations, the interfacecommunication units 105A/B employ multiple timer cycles. The timerscould count continuously throughout the multiple cycles or could bereset at each cycle. For example, as shown in FIG. 4, a second timercycle begins at time t8 and ends at time t15. The transmitter andreceiver timer information calculated by the interface controllers 320Aand 320B is used by the interface controllers 320A and 320B to calculatea round-trip propagation time (i.e., time of flight) for the propagationof the training information between each device.

FIG. 5 shows a block diagram illustrating a time of flight calculationof information exchanged between communication interface units 105. Eachof the nodes 1-4 represent one or a combination of components includedin a communication interface unit 105. In one example, a node includesthe interface controller 320, the transmitter circuit 305 or thereceiver circuit 310, and the transducer 315. In other examples, a nodeincludes alternative or additional components. As shown in FIG. 5, thecalculated time of flight of a round-trip path from any of nodes 1-4 isequivalent, and equal to the sum of the propagation times d0-d4 betweeneach node. In one embodiment, the propagation time between some nodes isspecified or known because a pair of nodes is located on the samecommunication interface unit 105. In one example, a first pair of nodesincludes node 1 and node 4 and a second pair of nodes includes node 2and node 3. In this example, the first pair of nodes represents thetransmitter circuit 305A and the receiver circuit 310A, and the secondpair of nodes represents the receiver circuit 310B and the transmittercircuit 305B. The propagation time between nodes included in the firstpair of nodes or the second pair of nodes may be programmed or otherwisestored in a memory accessible by the respective communication interfaceunit 105. Alternatively, other parameters, such as the distance betweennodes included in the first or second pair of nodes or other parametersfrom which the propagation time may be inferred or calculated, may bestored in a memory accessible by the respective communication interfaceunit 105.

In one implementation, the time of flight calculation is performedmultiple times and the results are averaged to determine an average timeof flight, which may be used as a seed for encrypting informationexchanged between the communication device 100 and the computing device300. In one implementation, the time of flight calculation is performedat a specified time or interval time, such as during power-up of thecommunication device 100 or the computing device 300, when data is notbeing transmitted (e.g., during an idle period) between thecommunication device 100 and the computing device 300, or at a specifiedinterval in accordance with the system requirements. The interfacecontroller 320A/B then stores the value of the calculated time of flightin memory accessible by the respective devices for further processing.In another embodiment, the interface controllers 320A/B calculate thetime of flight between each device during transport mode in a mannersimilar to that as described during link-training mode.

By employing multiple timer cycles, the interface communication units105 can more accurately calculate the round-trip propagation time ofinformation exchanged between the communication interface units 105A/B.Accordingly, the calculated time of flight of the training informationmay be used as a seed to generate an encryption key as further describedin conjunction with FIG. 6.

Returning to FIG. 3B, in one embodiment, the interface controller 320Aincludes circuitry to detect the frequency of an EHF transmission signalreceived during link-training mode or transport mode and uses themeasurement of the detected frequency to generate an indication ofproximity of the communication interface unit 105A to a nearby object.The presence of a nearby object, e.g., the computing device 300,sufficiently close to the transducer 315A causes the frequency of thedetected signal to vary based on the presence and proximity of thenearby object, as further described in U.S. patent application Ser. No.13/524,963, which is incorporated by reference in its entirety. Theinterface controller 320 is further configured to use other attributes(e.g., measure of transmission strength or calibration informationspecifying receiver threshold energy) of the detected EHF transmissionto determine the distance between corresponding communication interfaceunits. In another embodiment, the communication device 100 and/or thecomputing device 300 identification information is exchanged between thetwo devices.

In one embodiment, during the transport mode the interface controller320 is configured to establish an authentication protocol by which thecommunication device 100 can regulate access by other devices to aportion of information stored on memory device 110 as further describedin conjunction with FIG. 6. In one embodiment, the interface controller320A uses attributes of the detected authentication EHF transmissionreceived during the link-training mode to encrypt the informationtransmitted by the transmitter circuit 305A to the computing device 300during transport mode to permit access to information stored on thecommunication device 100 by authorized devices. For example, theinterface controller 320A uses the calculated propagation time or timeof flight between devices as a basis or seed to encrypt data transmittedby the transmitter circuit 305A. The propagation time or time of flightbetween the communication device 100 and the computing device 300 iscalculated by the interface controller 320B included in the computingdevice 300 during link-training mode in a manner similar to thatdescribed for the communication device 100. In turn, the computingdevice 300 uses the propagation time or time of flight calculated by thecomputing device 300 to decrypt the encrypted information received fromthe communication device 100 and to encrypt information transmitted tothe communication device 100 by the computing device 300 duringtransport mode. In another embodiment, the interface controller 320Auses attributes (e.g. transmission property of the transmitter side ofthe transducer 320A) of the EHF transmission, received during thetransport mode as a seed to encrypt the information transmitted by thetransmitter circuit 305A to the computing device 300 during transportmode. Similarly, the interface controller 320B uses attributes of thedetected authentication EHF transmission received during the transportmode to encrypt the information transmitted by the transmitter circuit305B to the communication device 100 during transport mode.Alternatively, one or a combination of time of flight measurements,transmission property parameters, detected frequency of an EHFtransmission, or any parameter derived or calculated therefrom, may beused as a seed to encrypt information exchanged between withcommunication device 100 and the computing device 100.

In another embodiment, the interface controller 320 uses anauthentication code to verify that another device is permitted toexchange information with the communication device 100. Anauthentication code is a device identifier (e.g., multi-bit code) thatoperates as a device key. The authentication code (e.g., cryptographicalgorithm(s)) may be stored in a memory location accessible by thecommunication device 100, encoded by the interface controller 320A, andtransmitted by transmitter circuit 305A to the computing device 300.Alternatively, the authentication code may be stored in the transmittercircuit 305A/B, the receiver circuit 310A/B, or the interface controller320A/B. The interface controller 320B includes circuitry to decode theEHF transmission received from the transmitter circuit 305A, recover theauthentication code, and compare the recovered authentication code witha copy of an authentication code stored on the computing device 300 todetermine if the codes match, indicating an authorized device. In oneembodiment, the communication device 100 employs key exchange,High-bandwidth Digital Content Protection (HDCP), public key encryption,or other known encryption techniques to protect information exchangedbetween the communication device 100 and the computing device 300. Inone embodiment, one or more of device key information, authenticationcode, and other security-related information is stored in a read-onlypart of the communication device 100 (e.g., a protected region of thememory device 100 or within an integrated circuit that embodies thecommunication interface unit 105A.

FIG. 6 illustrates a block diagram of a communication interface unitthat includes an encryption module. As shown in FIG. 6, thecommunication interface unit 105A transmits encrypted information usinga seed 602 to generate an encryption key for encrypting the transmittedinformation. In one embodiment, the seed 602 includes one or acombination of the calculated round-trip propagation time, calculatedtransmission property of the transmitter side of a transducer, and thedetected frequency of an EHF transmission that serves as an input to akey generator 604. In one implementation, the key generator 604 isimplemented in hardware, such as using a linear feedback shift register(LFSR). In another implementation, the key generator 604 is implementedin software, or implemented using a combination of hardware andsoftware. The key generator 604 supplies the generated encryption key toan encryption module 606A1 and a decryption module 606A2.

In the transmitter path of the communication interface unit 105A, theencryption module 606A1 uses the encryption key as a basis to encode(encrypt) information received from the interface controller 320A1 inaccordance with an encryption scheme or protocol. The encryption module606A1 may employ one or more encryption algorithms, or a combination ofhardware and software to encode information using the generated key. Theencrypted information output by the encryption module 606A1 is receivedby the transmitter circuit 305A for transmission to the communicationinterface unit 105B.

The receiver path of the communication interface unit 105A operates in amanner similar to the transmitter path. In the receiver path of thecommunication interface unit 105A, the decryption module 606A2 uses theencryption key as a basis to decode (decrypt) information received fromencrypted information received by the receiver circuit 310A inaccordance with a decryption scheme or protocol. The decryption module606A2 employs one or more decryption algorithms, or a combination ofhardware and software to decode information using the key generated bythe key generator 604A. The decrypted information output by thedecryption module 606A2 is received by the interface controller 320A2for further processing. Accordingly, during the transport mode theinterface controllers 320 are configured to establish an authenticationprotocol by which the communication device 100 can regulate access byother devices to a portion of information stored on memory device 110.

Returning to FIG. 3B, although the components of the communicationdevice 100 are depicted as separate components, one or more componentsof the communication device 100 may be combined or otherwise integratedinto a single component. In one example, the communication interfaceunit 105A is integrated with the storage device controller 115. Inanother example, the communication interface unit 105 is integrated withmemory device 110.

In one embodiment, the computing device 300 is a storage device readerconfigured to access data stored on memory device 110 of thecommunication device 100. The computing device 300 includes a devicecontroller 325 that operates as a processor or controller to manage theoperations of the computing device 300. In another embodiment, thecomputing device 300 is a storage device with functionality similar tothe communication device 100. In one example, the computing device 300is an unencapsulated storage subsystem that may be stacked vertically orotherwise arranged to communicate with communication device 100. Inanother example, the computing device 300 is an encapsulated storagedevice, such as the communication device 100.

In one embodiment, the functionality of the communication device 100varies based on the computing device 300 in communication with thecommunication device 100. For example, the communication device 100 isconfigured to manage access to data stored on the communication device100 based on computing device 300 in communication with thecommunication device 100. Data, such as movies, may be accessed from thestorage device when the communication device 100 or the surface of anobject coupled to communicate with the communication device 100 comes incontact (i.e., contactless communication) with a particular computingdevice 300. By operating in such a manner, the pair of devices operatein conjunction to authenticate access to data stored on thecommunication device 100 based on a particular device pairing. Inanother embodiment, functionality of communication device 100 variesbased on the device type of the communication device 100 (e.g., mobilephone, imaging device, tablet computing device, etc.) and the computingdevice 300 in communication with the communication device 100. Forexample, when operating in communication with a computing device 300, acommunication device 100 included in a mobile phone operates as a localstorage device. In another example, when operating in communication witha computing device 300, a communication device 100 included in animaging device (e.g., a digital camera) operates as storage for anoperating system. In one embodiment, the communication device 100 allowsaccess to only certain portions of the memory device 110 based on one ormore attributes of the computing device 300. For example, based on theauthentication attributes of the computing device 300, a portion of thememory device 110 is made accessible to the computing device 300.

In one embodiment, the communication device 100 controls the operationof the computing device 300. Alternatively, the computing device 300controls the operation of communication device 100. That is, thecommunication device 100 operates as a data sink or a data sourcedepending on the pairing of the communication device 100 and thecomputing device. In another embodiment, multiple communication devices100 operate in a master/follower mode. In master/follower mode,information stored on a follower device is accessible responsive to amaster device being read by a computing device 300 and sending anindication to the follower device that the master device has been readby the computing device 300. In the master/follower mode, the mastercommunication device 100 is operative to provide access to a master keyto authenticate access to the follower communication device 100. Themaster and follower devices authenticate each other by employingauthentication techniques as previously described with reference to theinterface controllers 320 of FIG. 3A/B, or any similar technique.

In one embodiment, the computing device 300 performs a secure data trimof data stored on communication device 100. For example, the computingdevice 300 compares data stored on communication device 100 at a firsttime with data stored on the storage device at a later time to determineif the stored data has been removed or deleted, and to perform a securetrim into the storage location where the data has been removed ordeleted. In another embodiment, the computing device 300 periodicallylogs data or a record of the data transferred between the communicationdevice 100 and the computing device 300. The computing device 300 isfurther configured to identify unauthorized data (i.e., copyrighted dataor content determined as being unauthorized based on data accesspermissions determined based at least in part on the particular pairingof the communication device 100 with the computing device 300) during alogging operation. Upon a determination of existence of unauthorizeddata, the computing device 300 disables access to the unauthorized data.

In one embodiment, the particular pairing of a communication device 100with a computing device 300 alters the user profile of softwareexecuting on a device associated with the communication device 100. Forexample, a device, such as a tablet computing device or a mobile phonehas a personal user profile stored on a communication device 100included in the tablet or mobile phone. When the device establishescommunication with a computing device 300, the computing device 300removes the personal profile stored on the communication device 100, andreplaces the personal profile with a secured profile (e.g., workprofile) suitable to use in a secure location.

Access Control

For example, such functionality may be employed in an access controlsystem for managing access to a secure location, such as privatebuilding or office, government facility, or other location that mayprovide access to sensitive information. In this scenario, to gainaccess (e.g., check-in) to a secure location, a person places thecommunication device 100 in physical proximity to an access controlreader that incorporates the computing device 300. In one example,devices are in physical proximity when the distance between the deviceis less than or equal to a threshold distance sufficient for thecommunication device 100 and the computing device 300 to establish acommunication channel and exchange information, as described withreference to FIG. 3. When the devices are in physical proximity, thecomputing device 300 initiates a check-in process. During the check-inprocess the computing device 300 performs action to record time,location, and a device state of the communication device 100 used by auser to provide access to the secure location. For example, during thecheck-in process, the computing device 300 stores a time stamprepresenting when the communication device 100 paired with the computingdevice 300 of the access control reader. The computing device 300 sendsthe time stamp information to communication device 100 or computingsystem for the secure location, which in turn, stores one or acombination of time stamps, corresponding user identificationinformation, and location information in an access log. In anotherexample, the computing device 300 also determines whether there ispersonal data stored on the communication device 100, copies anydiscovered stored personal data to a secure location, and removes thepersonal data from the communication device 100. In one example, thecomputing device 300 identifies personal data based on file attributes,including file extension, file name, and associated applicationsoftware. Other common known techniques may be employed by the computingdevice 300 to identify personal data stored on the communication device100.

In one embodiment, during the check-in process the computing device 300also limits one more capabilities of the communication device 100. Forexample, during the check-in process the computing device 300 disablesimage capture, audio capture, and communication functionality of thecommunication device 100. In another example, the computing device 300also disables one or more capabilities of the communication device 100based on location of the communication device 100, where the location ofthe communication device 100 is determined based on global positioninginformation (GPS), Wi-Fi positioning information, or other locationinformation provided by the communication device 100.

In one embodiment, during the check-in process, the computing device 300loads a secure profile on the communication device 100 that providessecure communication access within the secure location withoutdisclosing passwords, network information, or other sensitive data tothe user. In another embodiment, the computing device 300 logs datastored on the communication device 100 at the time of check-in. In oneexample, the computing device 300 scans the logged data for viruses orunauthorized data, and removes or quarantines such data in a securelocation for further processing. In another example, during a check-outprocess the computing device 300 compares the logged data to a record ofthe data transferred to or stored on the communication device 100 afterthe check-in process. If the comparison indicates that the communicationdevice 100 accessed unauthorized information, the computing device 300will remove the corresponding files during the check-out process.

When exiting the secure location, the user causes the communicationdevice 100 to initiate the check-out process, where the user repeats theprocess of placing the communication device 100 in physical proximitywith the access control device equipped with a computing device 300. Theaccess control device, in turn, restores the communication device 100 toa pre-check-in state. For example, during the check-out process theaccess control device performs one or more of the following actions:removes the secure profile from the communication device 100, restoresthe user's personal data, and restores the communication device's 100capabilities to the state prior to entering the secure location.

In another embodiment, a communication device 100 operates as a key to ahome. In one example, an access point (e.g., door, garage door, etc.) ofa home includes one or more access control regions that include acomputing device 300. Like in the check-in/check-out example previouslydescribed, a person places the communication device 100 in physicalproximity to an access control panel that incorporates the computingdevice 300. The computing device 300, in turn, authenticates the userbased on information located on the computing device 300 and thecommunication device 100. In one example, the computing authenticatesthe user in accordance with an authentication protocol as previouslydescribed with reference to the interface controllers 320 included inthe respective pair of devices. In another example, the computing device300 operates in conjunction with the communication device 100 to performa multi-factor authentication. In one scenario, the communication device100 and the computing device 300 perform a two-factor authentication,where the communication device 100, along with one of a personalidentification number (PIN), a user's biometric information (e.g.,retina scan, thumb print, voice signature, etc.) maintained on thecomputing device 300 or communication device 100 is used to authenticatethe user's identity.

Once authenticated, the computing device 300 registers the authenticateduser's status to indicate the user is currently in the home, andaccesses the authenticated user's profile to execute access controlsettings associated with the authenticated user. Access control settingsspecify, for example, lighting, environmental, audio/visual, security,communication systems, or other home system controls. The access controlsettings may be stored in one or a combination of the communicationdevice 100 or the computing device 300 incorporated in the accesscontrol panel. In operation, the computing device 300 incorporated inthe access control panel communicates with other systems in the home toexecute the access control settings in accordance with the accesscontrol settings of a particular authenticated user. In some cases, theaccess control settings for a particular user specify variations basedon time of day, or based on whether other authenticated users areregistered as being home. Using the communication device 100, a userregistered as being at home may view the home access history. The homeaccess history specifies any users presently at home and informationabout when those users arrived home and any other detectable activity ofthe other users since they arrived home. The access history alsospecifies when a user leaves the home, because a registered user isderegistered by the computing device 300 when the user leaves. In oneexample, the computing device 300 and the communication device 100operate in a process similar to the previously described check-outprocess when a user leaves the home. For example, to lock the door whenexiting the home, the user places the communication device 100 inphysical proximity with an access control panel that incorporates thecomputing device 300. The computing device 300 re-authenticates theuser, executes any user access control settings (e.g., turn off lights,set timers, enable security system, etc.), and locks the door.

In another access control application, a check-in/check-out process,similar to that previously described may be used regulate access betweencountries at a border crossing location or when passing through customsat a transit station. In this application, a user wishing to enteranother country or region checks-in devices equipped with auser-accessible electronic storage medium at an access control system.During check-in, a communication device 100 is scanned for harmfulinformation, such as viruses, by a computing device 300 included in anaccess control system. In another example, during check-in, thecomputing device 300 accesses location information, network connectivityinformation, or other information that may indicate activity of the userassociated with the device, which may be potentially harmful to acountry or region regulating access. When exiting a region or a country,the computing device 300 performs a check-out process and scans thecommunication device 100 for unauthorized information (e.g.,confidential government information). If detected, such unauthorizedinformation is removed from the communication device 100 by thecomputing device 300 prior to completion of the check-out process.

In a further access control application, the pairing of a communicationdevice 100 with a computing system 300 included in an access controlsystem is used to regulate access to a venue requiring a ticket forentry. In one embodiment, a user receives a ticket for entry into aparticular event, such as a concert, sporting event, movie, or otherperformance. The received ticket is stored on the communication device100 in an electronic format capable of being read by the computingdevice 300 included in the access control system. For example, theticket may be stored as an image file format that includes a ticketidentifier, such as an optical machine readable representation of data(e.g., bar code, Quick Response (QR) code, etc.) identifying the ticket.When entering the venue or event location, the user initiates a check-inprocess by placing the communication device 100 that stores anelectronic representation of the ticket near an access control systeminterface that includes a computing device 300.

During the check-in process, the computing device 300 scans thecommunication device 100 and detects the ticket identifier or otherattribute of the ticket. The computing device 300 operates or alone orin conjunction with other computing systems at the event to authenticatethe detected ticket. Once authenticated, user associated with thecommunication device 100 is allowed entry into the event. In oneembodiment, responsive to the ticket being authenticated, the computingdevice 300 sends a notification to the communication device 100indicating that the ticket has been authenticated. In addition to thenotification, the computing device 300 may also send event information(e.g., event maps, application software, advertisements, offers forsale, coupons, seating charts, etc.) to the communication device 100 fordisplay to the user.

In another venue access control application, the pairing of acommunication device 100 with a computing system 300 included in anaccess control system is used to regulate the capturing of images ofobjects on display at the venue using the communication device 100. Invenues, such as a museum, taking pictures of exhibits or art work may beprohibited. In such a situation, images of museum objects may be sent toa communication device 100 by placing the communication device 100 inphysical proximity to an information transfer interface that includes acomputing device 300. In one embodiment, the computing device 300 sendsfor display on the communication device 100 one or more selections ofpreviously captured images to the communication device 100, or sends theoption to capture an image from an image capture device located in themuseum. In another embodiment, the computing device 300 sends one ormore selections to transfer information about the museum, museumexhibit, or other related information (e.g., advertisements, offers forsale, coupons, etc.) to the communication device 100 when the userplaces the communication device 100 in physical proximity to theinformation transfer interface. Additionally, an information transferinterface may be used in a similar manner for other applications or atother venues or locations, including amusement parks, cruise ships,raceways, weddings, photo booth kiosks, to send images or information toa communication device 100.

In a further access control application, a check-in/check-out process,similar to that previously described may be used to regulate access tooperation of a vehicle. In this application, during a check-in process auser places the communication device 100 in physical proximity to anaccess control panel on the vehicle that incorporates the computingdevice 300. The computing device 300, in turn, authenticates the userbased on information located on the computing device 300 and thecommunication device 100 used by the user to gain access to the vehicle.In one example, the computing device 300 authenticates the user inaccordance with an authentication protocol as previously described withreference to the interface controllers 320 included in the respectivepair of devices. In another example, the computing device 300 operatesin conjunction with the communication device 100 to perform amulti-factor authentication, such as that described with reference tothe home access control.

Once authenticated, the computing device 300 registers the authenticateduser's status to indicate the user is currently in the vehicle, andaccesses the authenticated user's profile to execute vehicle controlsettings associated with the authenticated user. Vehicle controlsettings specify, for example, time, place, and maximum operating speedfor operating the vehicle. These settings may be programmed by a user,such as the vehicle's owner, rental car company, car dealer, or otherperson or entity charged with control of the vehicle. The settings arecommunicated by the computing device 300 to the vehicle's drive controlsystems to execute the vehicle control settings. In some cases, theaccess control settings specify variations based on time of day, orwhether another user of a threshold age can be authenticated as being inthe vehicle at same time as the requesting user. For example, to complywith government regulations, a driver holding a limited use license ordriving permit, may be permitted to drive under only with another personabove a particular age. In this example, the requesting driver and theaccompanying drive would check-in to the vehicle access control systemusing separate communication devices 100 associated with the respectiveuser. When the access control system of the vehicle authenticates theidentity of both users, the requesting user would be allowed to operatethe vehicle in accordance with the vehicle access settings associatedwith requesting user.

In another example of vehicle access control, a communication device 100associated with a user and an access control system that includes acomputing device 300 is used to detect a potentially impaired driver.Like the previous vehicle access control, the driver initiates acheck-in process by placing the communication device 100 in physicalproximity to an access control panel on the vehicle that incorporatesthe computing device 300. The computing device 300, in turn,authenticates the user and initiates a driver assessment process.

In one embodiment, the driver assessment process includes determiningcurrent driving conditions and presenting for display on thecommunication device 100 a series of prompts to determine whether arequesting driver's ability to operate the vehicle might be impairedbased on the determined driving conditions and the current physicalstate of the requesting driver. In one example, the computing device 300interacts with one or a combination of the communication device 100 andthe vehicle's infotainment system to determine the time of day, whetherconditions, traffic conditions, and vehicle location. The vehiclelocation may be represented as, for example, geographic coordinates, astreet address, or proximity to one or more merchant locations thatoffer goods or services capable of impairing a person's ability tosafely operate a vehicle.

During the driver assessment process, the computing device 300 presentsone or more prompts to the user and receives one or more responses tothe prompts. The prompts are formatted as one or a combination of text,audio, symbols, images, or other visual or audio representationperceivable by a user using the communication device 100. For example,the prompt may be presented for display on the communication device 100as a game to test the driver's dexterity, response time, vision, orother cognitive ability that could impact one's ability to safelyoperate a vehicle. In one example, the prompt requests that the userenter a response by interacting with a display of the communicationdevice 100, speaking, or providing biometric information (eye trackinginformation or voice information for speech recognition) to thecommunication device 100.

The communication device 100 sends the received prompt responses to thecomputing device 300 for evaluation. The computing device 300 uses oneor more stored factors to score a response. Factors include, forexample, the substance of the response, the response time, or traininginformation (voice signature or eye tracking rate). The aggregate scoreof each factor is compared to a competency threshold based on drivingconditions. For example, in cases where the current driving conditionsdetected by the computing device 300 indicate a present time of 2:30 am,raining, and the car is located near a bar, the competency threshold ishigher than if the detected current driving conditions indicate apresent time of 10:00 am, sunny, and the car is located near a park. Incases where the aggregate score meets or exceeds competency threshold,the computing device 300 allows the requesting driver to operate thevehicle. Otherwise, the computing device 300 may disable or limitoperation of the vehicle, cause the communication device 100 to displayinformation for alternative modes of transportation, or send anotification to a designated entity or person that the requesting driverneeds assistance.

FIG. 7 illustrates a flowchart of a method for controlling access to acommunication device, according to one embodiment. To improve securitywhen communicating between the communication device 100 and thecomputing device 300, the interface controller 320 also manages theexchange of data between communication interface units 105 ofcorresponding devices by verifying that communication interface unit105B of the computing device 300 is within a predetermined range and ispart of a device identified as being authorized to communicate with thecommunication device 100 before or during a communication attempt. Thecommunication device 100 detects 705 a reflected EHF transmission from areflective surface associated with a computing device, communicationdevice, or other device that includes a communication interface unitcapable of communicating with the corresponding communication interfaceunit included in the communication device 100. The communication device100 analyzes 710 the reflected EHF transmission to detectcharacteristics of the reflected EHF transmission that may be used as anindicator of proximity of the communication device 100 to another devicein close proximity (1 mm-5 cm) to the communication device 100. Inanalyzing the reflected EHF transmission, the communication device 100employs known electromagnetic signal analysis techniques to EHFtransmissions, including time domain, frequency domain, impedancemeasurements techniques.

Using the analysis results, the communication device 100 determines 715whether distance between a first device and second device satisfies athreshold distance sufficient to exchange EHF transmissions between afirst and second communication interface units included in therespective devices. In one embodiment, an indication of the actual orrelative proximity between devices is determined based on a detectedchange in the transmission property of the transmitter side of atransducer included in the first device caused by the reflection of anEHF transmission off of a surface of the second device. In oneembodiment, an indication of proximity between the first device andsecond device is determined based on a calculation of the propagationtime of an EHF signal transmitted by the first device, received by thesecond device, and transmitted back to the first device. Using thecalculated propagation time, the proximity between the first device andthe second device may be determined. In another embodiment, anindication of proximity between the first device and second device isdetermined based on a calculation of the frequency of a reflected EHFsignal transmitted and received by the first device after reflection bya surface of the second device. The frequency of the received reflectedEHF transmission is proportional to the propagation delay of the EHFcommunication signal as previously described. Because the signalpropagation time through a distance D 330, as shown in FIG. 3, increasesas the distance D 330 increases, the frequency and propagation delay arerelated to the distance D 330. And thus the distance may be calculatedbased on a measure of the frequency of the reflected EHF transmissionreceived by the first device (e.g., the communication device 100). Infurther embodiments, one or a combination of the signal strength orother attributes of a reflected EHF transmission detected by the firstdevice may be used to determine the proximity between the first deviceand the second device. Upon a determination that the calculatedproximity between a first and second device is not within a thresholddistance, the communication device 100 prohibits information to beexchanged between the communication device 100 and another deviceattempting communication with the communication device 100 and returnsto step 715.

Upon a determination that the calculated proximity between a first andsecond device is within a threshold distance, the communication device100 permits 720 information to be exchanged between the communicationdevice 100 and another device attempting communication with thecommunication device 100. In permitting information to be exchangedbetween the two devices (e.g., the communication device 100 and thecomputing device 300) the interface controller 320A operates inconjunction with the transmitter circuit 305A to modulate thetransmission of information stored on memory device to the computingdevice 300 as previously described with respect to FIGS. 3A and 3B. Inone embodiment, the interface controller 320 encodes informationtransmitted by transmitter circuit 305 by employing one or moreencryption schemes. In one example, the interface controller 320 encodesinformation transmitted by the transmitter circuit 305 based on thecalculated measure of the time of flight of and EHF transmission fromthe transmitter of a first device to a receiver of a second device andvice versa. The calculated time of flight is known by both devices, andthus may be used as an encryption key. And because the time of flightbetween devices changes in a random manner, the time of flight operatesas a random encryption key generator that is used by the interfacecontroller 320 to provide a high measure of data transmission securitybetween the two devices. The interface controller 320 may execute one ormore known encryption algorithms using the time of flight as anencryption key to encode and decode information exchanged between thecommunication device 100 and computing device 300.

In one embodiment, upon a determination that the calculated proximitybetween a first and a second device is within a threshold distance, theinterface controller 320A employs an authentication protocol todetermine whether a device attempting to communicate with thecommunication device 100 is an authorized device. For example, thecommunication device 100 may use an authentication code to verify thatanother device is permitted to exchange information with thecommunication device 100. To determine whether a device is an authorizeddevice, the communication device 100 receives information including anauthentication code from a requesting device. In one embodiment, theauthentication code is received responsive to a query (e.g., a beaconsignal) from the communication device 100. In other embodiments, theauthentication code is sent by the computing device 300 independent ofreceiving a request or query from the communication device 100. Thecommunication device 100 recovers the authentication code, compares therecovered authentication code with an authentication code stored on thecommunication device 100 to determine if the codes match. The computingdevice 300 performs the same operation as the communication device 100to compare an authentication code received from the communication device100 with an authentication code stored on the computing device. If thecodes match on both devices, the communication device 100 operates asdescribed in step 720. Otherwise, the communication device 100 prohibitsinformation from being exchanged between the two devices, and returns toone of steps 705, 710, or 715.

Upon reading this disclosure, those of skill in the art will appreciatestill additional alternative designs for a portable communication devicethat includes a contactless secure communication interface. For example,although the interface controller 320A authenticates another device asbeing authorized to access data stored on the communication device 100based on one or more attributes of EHF transmissions from the computingdevice 300, the same principles of this disclosure are also applicableto alternative designs based on other types of signals transmitted orreceived by the communication device 100. Thus, while particularembodiments and applications of the specification have been illustratedand described, it is to be understood that the disclosure is not limitedto the precise construction and components disclosed herein and thatvarious modifications, changes and variations which will be apparent tothose skilled in the art may be made in the arrangement, operation anddetails of the method and apparatus of the present disclosure disclosedherein without departing from the spirit and scope of the presentdisclosure.

What is claimed is:
 1. A method for regulating access to informationlocated in a secure location, the method comprising: determining, by aninterface controller included in a computing device, whether a distancebetween a communication device and the computing device satisfies athreshold distance, the computing device included in an access controlreader located at the secure location; responsive to the distancebetween the communication device and the computing device satisfying thespecified threshold distance: establishing a communication channelbetween the communication device and the computing device, thecommunication channel enabling information exchange between thecommunication device and the computing device using extremely highfrequency (EHF) signals, identifying, by the computing device, contentstored in the communication device having at least one specified fileattribute, copying, by the computing device, the identified content to amemory location accessible by the computing device included in theaccess control reader, decoding the identified content by the computingdevice using encryption information that is generated based on acalculated measure of time of flight of an EHF transmission between thecommunication device and the computing device; and removing, by thecomputing device, the identified content from the communication device.2. The method of claim 1, wherein responsive to the distance between thecommunication device and the computing device satisfying the thresholddistance, disabling specified functionality of the communication device.3. The method of claim 2, wherein the specified functionality of thecommunication device includes wireless communication.
 4. The method ofclaim 2, wherein the specified functionality of the communication deviceincludes audio capture.
 5. The method of claim 2, wherein the specifiedfunctionality of the communication device includes video capture.
 6. Themethod of claim 2, wherein the specified functionality of thecommunication device is disabled when the communication device is at aspecified location within the secure location.
 7. The method of claim 1,wherein responsive to the distance between the communication device andthe computing device satisfying the threshold distance, loading a secureprofile on to the communication device.
 8. The method of claim 1,wherein responsive to the distance between the communication device andthe computing device satisfying the threshold distance, logging contentsstored on the communication device.
 9. A method for regulating access bya user to a secure location, the method comprising: determining, by aninterface controller included in a communication device, whether adistance between the communication device, associated with the user, andan access control device located at the secure location satisfies athreshold distance; responsive to the distance between the communicationdevice and the access control device satisfying the threshold distance,the communication device and the access control device exchangingcapability information describing functionality of the respectivedevices; authenticating, by the access control device, the user based atleast in part on the capability information; and encoding content sentby the interface controller using encryption information generated basedon a calculated measure of time of flight of an EHF transmission betweenthe communication device and the access control device.
 10. The methodof claim 9, further comprising receiving training information from thecommunication device, the training information specifying a data patternused by the access control device to select access control devicesettings to exchange information with the communication device over atransmission path.
 11. The method of claim 10, further comprisingauthenticating the user based at least in part on the traininginformation.
 12. The method of claim 10, further comprisingauthenticating the user based at least in part on the user's biometricinformation.
 13. The method of claim 9, wherein the capabilityinformation comprises a device type.
 14. The method of claim 9, whereinthe capability information comprises a transport mode.
 15. An accesscontrol system comprising: a computing device comprising: at least onetransmitter configured to transmit data using close proximity extremelyhigh frequency (EHF) electromagnetic energy to a communication deviceover a first transmission path, the communication device associated witha user; at least one receiver configured to receive data from thecommunication device over a second transmission path; an interfacecontrol circuit coupled to the at least one transmitter unit and the atleast one receiver and configured to: determine whether a distancebetween the communication device and the computing device satisfies athreshold distance, and responsive to the distance between thecommunication device and the computing device satisfying the thresholddistance, establish a communication channel between the communicationdevice and the computing device, the communication channel enablinginformation exchange between the communication device and the computerdevice using EHF signals; and a device controller coupled to theinterface control circuit and configured to: identify content stored onthe communication device having at least one specified file attributeresponsive to the distance between the communication device and thecomputing device satisfying the threshold distance, copy the identifiedcontent to a memory location accessible by the computing device, decodethe identified content using encryption information generated based on acalculated measure of the time of flight of an EHF transmission betweenthe communication device and the computing device, and remove theidentified content from the communication device.
 16. The access controlsystem of claim 15, wherein the device controller is configured todisable specified functionality of the communication device responsiveto the determined distance between the communication device and thecomputing device satisfying the threshold distance.
 17. The accesscontrol system of claim 16, wherein the specified functionality of thecommunication device includes wireless communication.
 18. The accesscontrol system of claim 16, wherein the specified functionality of thecommunication device includes audio capture.
 19. The method of claim 1,wherein the measure of the time of flight corresponds to a round trippropagation time between the communication device and the computingdevice.